Many wireless communication networks (e.g., cellular networks) now include a short messaging service (“SMS”). The SMS allows users with properly configured wireless devices to send short alphanumeric messages (“text messages”) to one another over the network. To send a text message, the message is keyed into the user's wireless device along with a communication identifier for contacting the recipient. The communication identifier may be the recipient's mobile phone number or, depending on the particular network and SMS system, it may be a messaging address or number, e.g., a streamlined number or address designated for text messaging. The network processes the text message for routing to the recipient. Message length is usually limited to 80-160 characters.
Generally speaking, since all that is required to send a text message is a valid recipient communication identifier, network users can send anonymous or non-solicited text messages to other users. For example, a user may be able to obtain communication identifiers from sources such as telephone directories, purchased mailing lists, or Internet harvesting. Accordingly, as with “spam” in the context of e-mail communications and unsolicited phone calls from telemarketers in the context of a public switched telephone network (“PSTN”), SMS users are subjected to receiving unwanted text messages. Besides being generally annoying in nature, such messages tie up a user's communication resources, e.g., wasted bandwidth and memory usage. Moreover, the recipient user has to take the time to read and delete the unsolicited or unwanted text messages.